Generally, photographic processing of a silver halide color phonographic material comprises a color developing step and a silver removing (desilvering) step. Silver formed by development is oxidizing with a bleaching agent and then dissolved with a fixing agent.
A ferric (III) ion complex salt (e.g., an aminopolycarboxylic acid-iron (III) complex salt) is usually used as the bleaching agent and a thiosulfate is usually used as a fixing agent.
Also, processing of a black and white photographic material comprises a development step and a step of removing unexposed silver halide. Unlike processing of a color photographic material, the black and white photographic material is fixed after development without being bleached. In this case, as the fixing agent, a thiosulfate is usually also used.
Recently, with the development of low replenishing techniques, a more stable liquid composition has been desired for each processing bath. As to a fix bath, since the thiosulfate generally contained therein tends to be deteriorated by oxidation, sulfurized and precipitated; a sulfite is usually added to the fix bath as a preservative for preventing the occurrence of the oxidation. However, with the further development of low replenishing techniques, there is yet a further need for improvement of the stability of each processing liquid. However, such improvement is not attained by an increase in the addition amount of sulfite due to the solubility limit of the sulfite. Furthermore, when the sulfite is oxidized, Glauber's salt is precipitated.
On the other hand, from the view point of promoting rapid photographic processing, the development of a compound having a fixing property superior to thiosulfate has been desired.
In view of the above, there is a need in the art for the development of a fixing agent having excellent stability to oxidation and an excellent fixing property in place of thiosulfate; however such a compound having the above described properties has not hitherto been known.